Flexible polyurethane foams are commonly made by reacting petroleum-derived polyols or polyol compositions with organic polyisocyanates in the presence of catalysts, blowing agents and other optional ingredients. Since the 1960's, flexible polyurethane foams have been used as a cushioning, load-bearing, and comfort-providing component of automotive, bedding and transportation.
In producing flexible polyurethane foams, several properties of the polyols or polyol compositions used are important for manufacturing flexible foams that have desirable characteristics. One important polyol property is the number average hydroxyl functionality of the polyol. Typically, to form a flexible polyurethane foam having desirable characteristics, a polyol having a number average hydroxyl functionality of about 3 is desired. It is conventionally understood that as the number average hydroxyl functionality decreases from that desired range, the quality of the polyurethane polymer network is lost and the foam characteristics quickly degrade. Once the number average functionality is 3.0 or less, it is expected that stable open cell foam will not form or if formed will have such poor physical properties that it will not be useful.
Polyurethane foam properties can be measured by various methods. In general, foams may be measured for tensile strength, tear, hardness, elongation, compression, and other properties. The relative importance of the properties varies, depending upon the expected use of the foam.
Petroleum-derived polyols have been widely used in the manufacturing of foams. However, there has been an increased interest in the use of renewable resources in the manufacturing of foams. This has led to research into developing vegetable oil-based polyols for use in the manufacturing of foams.
Other researchers have tried to make flexible foam from biobased polyols. WO 2004/096883A1 and WO2004/09882A1 report how to make TDI-based conventional slabstock foams from biobased polyol formulations and provide physical properties of the resulting foams. The reported biobased polyols have a number average hydroxyl functionality greater than 2.8.